Generally, shipping companies determine an amount to charge for the transport of customer packages based on a relatively limited number of factors, including the package's weight, dimensions and distance to the shipping destination. If the customer expects a package to be delivered to the correct address, the customer is required to provide the shipping company with the correct destination, and there may be a relatively high degree of confidence, therefore, in revenue based on shipping distance and/or destination address. On the other hand, customers often will not have ready access to accurate information regarding the dimensions and weight of the packages they ship.
Particularly with the increase in use of online resources, shipping companies often allow customers to provide the weight, dimension, and destination of their packages prior to collection for shipment. Customers may provide such information through an Internet site or on a paper record attached to the package itself and then deposit the package in an unattended drop-off container from which the carrier retrieves the package. Packages may also be shipped through third-party storefronts or corporate shipping departments. The carrier may not check dimension and weight information for accuracy prior to collection. Thus, the revenue collected for such packages may be understated due to the discrepancy between the declared and actual weights and dimensions.
Systems are known that weigh and scan bar codes on packages in-motion on a conveyor system so that package weights can be compared against declared weights. Such systems may include an in-motion scale under a short section of moving conveyor disposed between an upstream main system conveyor and a downstream main system conveyor and a laser based bar code scanner located on the upstream or downstream main system conveyor or over the scale. The system also includes a dimensioner, a processor and a tachometer. As should be understood in this art, dimensioners detect one or more dimensions of an item on a conveyor. Various types of dimensioners are known, and it should be understood by those skilled in the art that dimensioners can be constructed in a variety of configurations, for example employing laser scanners that produce return signals describing the spatial configuration of an item passing proximate the dimensioner.
The tachometer is coupled to the upstream main system conveyor so that the conveyor's movement causes the tachometer to output pulses corresponding to the distance the conveyor moves and its speed. The dimensioner is disposed along the conveyor at a known position relative to the scale. When a package moving along the conveyor reaches the dimensioner, the dimensioner processor opens a package record, determines height, width and length, associates that data in the package record, and outputs the dimension data to the system processor in association with tachometer data that corresponds to the package's location at the dimensioner. Upon receiving the dimensioner data, the system processor opens a package record and associates with the package record the dimension and tachometer data received from the dimensioner. The system processor also sets an open read window variable and a close read window variable for the barcode scanner, and an open read window variable and a close read window variable for the scale. The open read window variable for the scale is equal to the tachometer value for the downstream-most point on the package, plus a known distance (in tachometer pulses) between the dimensioner and a predetermined position in the path of travel with respect to the scale. The close read window variable for the scale is equal to the tachometer value for the upstream-most point on the package, plus a known distance (in tachometer pulses) between the dimensioner and the predetermined position with respect to the scale. The open read window variable for the barcode scanner is equal to the tachometer value for the downstream-most point on the package, plus a known distance (in tachometer pulses) between the dimensioner and a predetermined position in the path of travel with respect to the barcode scanner. The close read window variable for the barcode scanner is equal to the tachometer value for the upstream-most point on the package, plus a known distance (in tachometer pulses) between the dimensioner and the predetermined position with respect to the barcode scanner.
The scale may have a generally planar top surface over which the conveyor belt passes. As a package moves over the scale, the package weighs down onto the scale's top surface such that one or more load cells depressed by the scale's top surface generate signals to the processor corresponding to the package's weight. The scale assembly has a photodetector disposed along the short conveyor immediately upstream from the scale. A processor on the scale monitors the photodetector's output signal and thereby determines when the package's front and back edges pass the photodetector. The scale also receives the tachometer output. By associating the passage of the package's front and back edges by the photodetector with the tachometer values corresponding to those events, the scale processor determines the package's length. The rate at which the tachometer outputs pulses to the scale determines how fast the package is moving through the path of travel, and this, along with package length, determines the time following its passage by the photodetector at which the package will have been on the scale a sufficient time for the scale to validly acquire the package's weight. The scale processor accordingly determines when valid weight data may be acquired for the package and acquires the weight data at that point.
The scale processor transmits weight data to the system processor when a package reaches a predetermined point in the path of travel following the scale. More specifically, the scale processor knows when the front edge of the package passes by the scale photodetector. After acquiring the package's weight at a point based on the package's length and belt speed, the scale processor holds the weight data until a tachometer value the scale associates with the weight data based on the photodetector signal accumulates to a point indicating that the front edge of the package is at a predetermined point downstream of the scale. The scale processor then outputs the weight data to the system processor.
The system processor relies on tachometer pulses to correctly associate weight data with a package record. The system processor determines the accumulated tachometer value at the time the weight data is received from the scale processor. The open read window and close read window scale variables for each package record correspond to the distance between the dimensioner and the predetermined point downstream from the scale. Thus, the system processor compares the tachometer value associated with the received weight data with the open read window and close read window variables for the open package structures it maintains. If the tachometer value is between the open read window scale variable and close read window scale variable for any open package record (because the scale processor transmits weight data when the package's leading edge reaches the predetermined point, the tachometer value should be near the open read window scale variable), the system processor assigns the weight data to that package record. If the tachometer value does not fall within the open window and close window scale variables stored for any open package record, the weight data is not assigned to a package record.
As should be understood in this art, a barcode reader may comprise a laser scanner that projects a plurality of laser lines on the belt, for example in a series of “X” patterns. The scanner outputs a signal that includes barcode information reflected back from the laser lines and a barcode count, which indicates the position in the X patterns at which given barcode information was seen. Thus, the barcode count provides the lateral position on the belt, and the longitudinal position with respect to the centerline of the X patterns, corresponding to the barcode information. The barcode scanner assembly has a photodetector disposed along the short conveyor immediately upstream from the X patterns. A processor at the barcode scanner assembly monitors the photodetector's output signal and thereby determines when the package's front and back edges pass the photodetector. The barcode scanner also receives the tachometer output. By associating the passage of the package's front and back edges by the photodetector with the tachometer data, the barcode scanner processor determines when the package passes through the X patterns. The barcode scanner processor accordingly determines when valid barcode data may be acquired for the package, acquires the barcode data during that period.
The barcode processor accumulates barcode data while a given package passes through the X patterns and transmits the accumulated barcode data to the system processor when the package reaches a predetermined point in the path of travel following the barcode scanner. More specifically, the barcode scanner processor knows when the front edge of the package passes by the barcode scanner photodetector. After acquiring the package's barcode data over a period based on the package's length, the barcode scanner processor holds the barcode data until a tachometer value the barcode scanner processor associates with the barcode data accumulates to a point indicating that the front edge of the package is at the predetermined point downstream of the scanner. The predetermined point is defined so that the longest package the system is expected to handle can clear the scanner's X patterns. The barcode scanner processor then outputs the barcode data to the system processor.
The system processor relies on tachometer pulses to correctly associate barcode data with a package record. The system processor determines the accumulated tachometer value at the time the barcode data is received from the barcode scanner processor. The open read window and close read window barcode variables for each package structure correspond to the distance between the dimensioner and the predetermined point downstream from the barcode scanner. Thus, the system processor compares the tachometer value associated with the received barcode data with the open read window and close read window barcode variables for the open package structures it maintains. If the tachometer value is between the open read window barcode variable and close read window barcode variable for any open package structure, the system processor assigns the barcode data to that package record. If the tachometer value does not fall within the open window and close window barcode variables stored for any open package record, the barcode data is not assigned to a package record.
Such known systems are operable with items that do not overlap with respect to the conveyor's direction of travel. The scale photodetector detects gaps between the items, and even where the gaps are short enough that there are first periods in which two items are simultaneously on the scale, if there are second periods of time in which respective items are on the scale alone for a time sufficient to allow the scale to settle, valid weight data may be acquired.
In the operation of conveyor systems processing non-overlapping items, it is known that the items may become overlapped in certain circumstances, for example when a sudden increase in items received at a receiving station cause human operators to load items on the conveyor at a rate higher than that necessary to maintain item separation. If the items become overlapped, multiple items may be on the scale when the processor receives weight data, and the weight data is therefore unreliable and unusable. Thus, it is known to provide a switch that discontinues the communication of weight data from the scale to the processor so that a human operator detecting an overlapped condition can manually interrupt the weighing function.
It is known to dispose a dimensioner at a predetermined position upstream from a barcode scanner within a conveyor system that carries overlapping items and that does not include a scale, where the dimensioner is configured to determine the position and orientation of each item, for example a package, on the conveyor belt and, based on expected package shapes, whether packages are adjacent each other. The distance, and therefore the number of tachometer pulses corresponding to the distance, between the dimensioner and the centerline of the barcode scanner's X pattern is known, and the dimensioner uses this distance to define the four corners of each package as it relates to the position of the center of the scanner's X pattern.
The tachometer values are synchronized between the system processor and the barcode scanner processor, so that both processors accumulate the same tachometer value. The barcode scanner's processor constantly monitors incoming barcode data and outputs the data as it is received, along with the accumulated tachometer value, a variable that identifies the particular leg, or scan line, of the X pattern in which the barcode was read, and the relative barcode count, to the system processor. The system processor subtracts from the tachometer value associated with the received barcode data a tachometer value corresponding to the longitudinal offset represented by the barcode count, thereby normalizing the tachometer value to the centerline of the X pattern. Based on the adjusted tachometer value and the barcode's lateral position, the system processor determines whether the barcode falls within the four corners of any package (accounting, as discussed above, for the longitudinal distance between the dimensioner and the barcode scanner), taking into consideration the package's height if the barcode were to have been read on that package. As should be understood in this art, package height determines the size of the X's in the X pattern seen by the barcode scanner, and the package height is therefore needed to accurately determine the barcode's normalized tachometer value and lateral position. If, following adjustment for package height, the location of the barcode falls within the four corners of a package, the system processor assigns the barcode data to that package record. If the barcode data does not match any open package record, the barcode data is not assigned to a package record.